@inproceedings{322, abstract = {{Reputation systems are used to compute and publish reputation scores for services or products. We consider reputation systems where users are allowed to rate products that they purchased previously. To obtain trustworthy reputations, they are allowed to rate these products only once. As long as users rate products once, they stay anonymous. Everybody is able to detect users deviating from the rate-products-only-once policy and the anonymity of such dishonest users can be revoked by a system manager. In this paper we present formal models for such reputation systems and their security. Based on group signatures presented by Boneh, Boyen, and Shacham we design an efficient reputation system that meets all our requirements.}}, author = {{Blömer, Johannes and Juhnke, Jakob and Kolb, Christina}}, booktitle = {{Proceedings of the 18th International Conference on Financial Cryptography and Data Security (FC)}}, pages = {{478----488}}, title = {{{Anonymous and Publicly Linkable Reputation Systems}}}, doi = {{10.1007/978-3-662-47854-7_29}}, year = {{2015}}, } @article{3892, abstract = {{Plasmon modes of the exact same individual gold nanoprisms are investigated through combined nanometer-resolved electron energy-loss spectroscopy (EELS) and cathodoluminescence (CL) measurements. We show that CL only probes the radiative modes, in contrast to EELS, which additionally reveals dark modes. The combination of both techniques on the same particles thus provides complementary information and also demonstrates that although the radiative modes give rise to very similar spatial distributions when probed by EELS or CL, their resonant energies appear to be different. We trace this phenomenon back to plasmon dissipation, which affects in different ways the plasmon signatures probed by these techniques. Our experiments are in agreement with electromagnetic numerical simulations and can be further interpreted within the framework of a quasistatic analytical model. We therefore demonstrate that CL and EELS are closely related to optical scattering and extinction, respectively, with the addition of nanometer spatial resolution.}}, author = {{Losquin, Arthur and Zagonel, Luiz F. and Myroshnychenko, Viktor and Rodríguez-González, Benito and Tencé, Marcel and Scarabelli, Leonardo and Förstner, Jens and Liz-Marzán, Luis M. and García de Abajo, F. Javier and Stéphan, Odile and Kociak, Mathieu}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{tet_topic_plasmonics}}, number = {{2}}, pages = {{1229--1237}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Unveiling Nanometer Scale Extinction and Scattering Phenomena through Combined Electron Energy Loss Spectroscopy and Cathodoluminescence Measurements}}}, doi = {{10.1021/nl5043775}}, volume = {{15}}, year = {{2015}}, } @article{3894, abstract = {{We show how to optically connect guiding layers at different elevations in a 3-D integrated photonic circuit. Transfer of optical power carried by planar, semi-guided waves is possible without reflections or radiation losses, and over large vertical distances. This functionality is realized through simple step-like folds of high-contrast dielectric slab waveguides, in combination with oblique wave incidence, and fulfilling a resonance condition. Radiation losses vanish, and polarization conversion is suppressed for TE wave incidence beyond certain critical angles. This can be understood by fundamental arguments resting on a version of Snell’s law. The two 90° corners of a step act as identical partial reflectors in a Fabry–Perot-like resonator setup. By selecting the step height, i.e., the distance between the reflectors, one realizes resonant states with full transmission. Rigorous quasi-analytical simulations for typical silicon/silica parameters demonstrate the functioning. Combinations of several step junctions can lead to other types of optical on-chip connects, e.g., U-turn- or bridge-like configurations.}}, author = {{Hammer, Manfred and Hildebrandt, Andre and Förstner, Jens}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, keywords = {{tet_topic_waveguide}}, number = {{16}}, pages = {{3711--3714}}, publisher = {{The Optical Society}}, title = {{{How planar optical waves can be made to climb dielectric steps}}}, doi = {{10.1364/ol.40.003711}}, volume = {{40}}, year = {{2015}}, } @article{3896, abstract = {{We study the formation of subwavelength solitons in binary metal-dielectric lattices. We show that the transverse modulation of the lattice constant breaks the fundamental plasmonic band and suppresses the discrete diffraction of surface plasmon waves. New types of plasmonic solitons are found, and their characteristics are analyzed. We also demonstrate the existence of photonic-plasmonic vector solitons and elucidate their propagation properties.}}, author = {{Kou, Yao and Förstner, Jens}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, keywords = {{tet_topic_polariton}}, number = {{6}}, pages = {{851--854}}, publisher = {{The Optical Society}}, title = {{{Subwavelength binary plasmonic solitons}}}, doi = {{10.1364/ol.40.000851}}, volume = {{40}}, year = {{2015}}, } @article{3900, abstract = {{The coherent state preparation and control of single quantum systems is an important prerequisite for the implementation of functional quantum devices. Prominent examples for such systems are semiconductor quantum dots, which exhibit a fine structure split single exciton state and a V-type three level structure, given by a common ground state and two distinguishable and separately excitable transitions. In this work we introduce a novel concept for the preparation of a robust inversion by the sequential excitation in a V-type system via distinguishable paths.}}, author = {{Mantei, D. and Förstner, Jens and Gordon, S. and Leier, Y. A. and Rai, A. K. and Reuter, Dirk and Wieck, A. D. and Zrenner, Artur}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, keywords = {{tet_topic_qd}}, number = {{1}}, pages = {{10313}}, publisher = {{Springer Nature}}, title = {{{Robust Population Inversion by Polarization Selective Pulsed Excitation}}}, doi = {{10.1038/srep10313}}, volume = {{5}}, year = {{2015}}, } @inbook{2921, author = {{Blazy, Olivier and Kakvi, Saqib and Kiltz, Eike and Pan, Jiaxin}}, booktitle = {{Lecture Notes in Computer Science}}, isbn = {{9783662464465}}, issn = {{0302-9743}}, pages = {{256--279}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Tightly-Secure Signatures from Chameleon Hash Functions}}}, doi = {{10.1007/978-3-662-46447-2_12}}, year = {{2015}}, } @misc{301, author = {{Bobolz, Jan}}, publisher = {{Universität Paderborn}}, title = {{{Efficient Verifier-Local Revocation for Anonymous Credentials}}}, year = {{2015}}, } @techreport{2730, author = {{Gries, Thomas and Grundmann, Rainer and Palnau, Irene and Redlin, Margarete}}, pages = {{100}}, title = {{{Does technological change drive inclusive industrialization? - A review of major concepts and findings}}}, volume = {{2015-044}}, year = {{2015}}, } @inproceedings{1142, author = {{Geierhos, Michaela and Bäumer, Frederik Simon}}, booktitle = {{DHd 2015: Book of Abstracts}}, location = {{Graz, Austria}}, pages = {{69--72}}, publisher = {{ZIM-ACDH}}, title = {{{Erfahrungsberichte aus zweiter Hand: Erkenntnisse über die Autorschaft von Arztbewertungen in Online-Portalen}}}, year = {{2015}}, } @article{1143, abstract = {{Der Erfahrungsaustausch zwischen Patienten findet heutzutage zunehmend im Internet statt. Bewertungsportale wie jameda, DocInsider oder imedo.de bieten Patienten und deren Angehörigen die Möglichkeit, anonym Beschwerden zu äußern oder Weiterempfehlungen auszusprechen. Gleichzeitig ermöglichen diese hunderttausend Individualerfahrungen die Erhebung der Patientenzufriedenheit sowie die Überprüfung bestehender Gerüchte, wie z. B. dass Privatpatienten schneller einen Arzttermin bekommen und weniger Zeit im Wartezimmer verbringen. Die Analyse anonymer Online-Arztbewertungen kann nur dann erfolgreich sein, wenn bei der Interpretation der Patientenerfahrungsberichte berücksichtigt wird, dass behandlungsqualitätsunabhängige Faktoren Auswirkungen auf die subjektive Bewertung und das Beschwerdeverhalten haben. Ein neuer Ansatz ist daher, bedeutende Indikatoren für die Patientenzufriedenheit im Web 2.0 zur Generierung eines detaillierten Erfahrungs- und Patientenstimmungsbildes unter Berücksichtigung demographischer und regionaler Einflüsse zu ermitteln.}}, author = {{Geierhos, Michaela and Schulze, Sabine}}, journal = {{ForschungsForum Paderborn}}, pages = {{14--19}}, publisher = {{Universität Paderbon}}, title = {{{Der zufriedene Patient 2.0: Analyse anonymer Arztbewertungen zur Generierung eines Patientenstimmungsbildes}}}, volume = {{18}}, year = {{2015}}, } @techreport{233, abstract = {{Motivated by the deterministic single exponential time algorithm of Micciancio and Voulgaris for solving the shortest and closest vector problem for the Euclidean norm, we study the geometry and complexity of Voronoi cells of lattices with respect to arbitrary norms.On the positive side, we show that for strictly convex and smooth norms the geometry of Voronoi cells of lattices in any dimension is similar to the Euclidean case, i.e., the Voronoi cells are defined by the so-called Voronoi-relevant vectors and the facets of a Voronoi cell are in one-to-one correspondence with these vectors. On the negative side, we show that combinatorially Voronoi cells for arbitrary strictly convex and smooth norms are much more complicated than in the Euclidean case.In particular, we construct a family of three-dimensional lattices whose number of Voronoi-relevant vectors with respect to the l_3-norm is unbounded.Since the algorithm of Micciancio and Voulgaris and its run time analysis crucially dependonthefactthatfortheEuclidean normthenumber of Voronoi-relevant vectors is single exponential in the lattice dimension, this indicates that the techniques of Micciancio and Voulgaris cannot be extended to achieve deterministic single exponential time algorithms for lattice problems with respect to arbitrary l_p-norms.}}, author = {{Blömer, Johannes and Kohn, Kathlén}}, publisher = {{Universität Paderborn}}, title = {{{Voronoi Cells of Lattices with Respect to Arbitrary Norms}}}, year = {{2015}}, } @inproceedings{5678, abstract = {{Many academic disciplines - including information systems, computer science, and operations management - face scheduling problems as important decision making tasks. Since many scheduling problems are NP-hard in the strong sense, there is a need for developing solution heuristics. For scheduling problems with setup times on unrelated parallel machines, there is limited research on solution methods and to the best of our knowledge, parallel computer architectures have not yet been taken advantage of. We address this gap by proposing and implementing a new solution heuristic and by testing different parallelization strategies. In our computational experiments, we show that our heuristic calculates near-optimal solutions even for large instances and that computing time can be reduced substantially by our parallelization approach.}}, author = {{Rauchecker, Gerhard and Schryen, Guido}}, booktitle = {{Australasian Conference on Information Systems}}, keywords = {{scheduling, decision support, heuristic, high performance computing, parallel algorithms}}, pages = {{1--13}}, title = {{{High-Performance Computing for Scheduling Decision Support: A Parallel Depth-First Search Heuristic}}}, year = {{2015}}, } @article{5679, abstract = {{Cloud computing promises the flexible delivery of computing services in a pay-as-you-go manner. It allows customers to easily scale their infrastructure and save on the overall cost of operation. However Cloud service offerings can only thrive if customers are satisfied with service performance. Allow-ing instantaneous access and flexible scaling while maintaining the service levels and offering competitive prices poses a significant challenge to Cloud Computing providers. Furthermore services will remain available in the long run only if this business generates a stable revenue stream. To address these challenges we introduce novel policy-based service admission control mod-els that aim at maximizing the revenue of Cloud providers while taking in-formational uncertainty regarding resource requirements into account. Our evaluation shows that policy-based approaches statistically significantly out-perform first come first serve approaches, which are still state of the art. Furthermore the results give insights in how and to what extent uncertainty has a negative impact on revenue.}}, author = {{Püschel, Tim and Schryen, Guido and Hristova, Diana and Neumann, Dirk}}, journal = {{European Journal of Operational Research}}, keywords = {{admission control, informational uncertainty, revenue management, cloud computing}}, number = {{2}}, pages = {{637--647}}, publisher = {{Elsevier}}, title = {{{Revenue Management for Cloud Computing Providers: Decision Models for Service Admission Control under Non-probabilistic Uncertainty}}}, volume = {{244}}, year = {{2015}}, } @unpublished{749, author = {{Dräxler, Sevil and Karl, Holger}}, booktitle = {{CoRR}}, title = {{{Specification of Complex Structures in Distributed Service Function Chaining Using a YANG Data Model}}}, year = {{2015}}, } @inproceedings{5541, author = {{Yasasin, Emrah and Schryen, Guido}}, booktitle = {{23rd European Conference on Information Systems (ECIS 2015)}}, title = {{{Requirements for IT Security Metrics - An Argumentation Theory Based Approach}}}, year = {{2015}}, } @inproceedings{5588, abstract = {{The protection of information technology (IT) has become and is predicted to remain a key economic challenge for organizations. While research on IT security investment is fast growing, it lacks a theoretical basis for structuring research, explaining economic-technological phenomena and guide future research. We address this shortcoming by suggesting a new theoretical model emerging from a multi-theoretical perspective adopt-ing the Resource-Based View and the Organizational Learning Theory. The joint appli-cation of these theories allows to conceptualize in one theoretical model the organiza-tional learning effects that occur when the protection of organizational resources through IT security countermeasures develops over time. We use this model of IT security invest-ments to synthesize findings of a large body of literature and to derive research gaps. We also discuss managerial implications of (closing) these gaps by providing practical ex-amples.}}, author = {{Weishäupl, Eva and Yasasin, Emrah and Schryen, Guido}}, booktitle = {{International Conference on Information Systems}}, keywords = {{Information Security, Investment, Literature review, Resource-based View, Organi-zational Learning Theory, Multi-theoretical Perspective}}, title = {{{A Multi-Theoretical Literature Review on Information Security Investments using the Resource-Based View and the Organizational Learning Theory}}}, year = {{2015}}, } @inproceedings{5589, author = {{Weishäupl, Eva and Yasasin, Emrah and Schryen, Guido}}, booktitle = {{23rd European Conference on Information Systems (ECIS 2015)}}, title = {{{IT Security Investments Through the Lens of the Resource-Based View: A new Theoretical Model and Literature Review}}}, year = {{2015}}, } @inproceedings{5590, abstract = {{Nowadays, providing employees with failure-free access to various systems, applications and services is a crucial factor for organizations? success as disturbances potentially inhibit smooth workflows and thereby harm productivity. However, it is a challenging task to assign access rights to employees? accounts within a satisfying time frame. In addition, the management of multiple accounts and identities can be very onerous and time consuming for the responsible administrator and therefore expensive for the organization. In order to meet these challenges, firms decide to invest in introducing an Identity and Access Management System (IAMS) that supports the organization by using policies to assign permissions to accounts, groups, and roles. In practice, since various versions of IAMSs exist, it is a challenging task to decide upon introduction of an IAMS. The following study proposes a first attempt of a decision support model for practitioners which considers four alternatives: Introduction of an IAMS with Role-based Access Control RBAC) or without and no introduction of IAMS again with or without RBAC. To underpin the practical applicability of the proposed model, we parametrize and operationalize it based on a real world use case using input from an expert interview.}}, author = {{Weishäupl, Eva and Kunz, Michael and Yasasin, Emrah and Wagner, Gerit and Prester, Julian and Schryen, Guido and Pernul, Günther}}, booktitle = {{2nd International Workshop on Security in highly connected IT Systems (SHCIS?15)}}, keywords = {{Identity and Access Management, Economic Decision Making, Information Systems, Information Security Investment, Decision Theory}}, title = {{{Towards an Economic Approach to Identity and Access Management Systems Using Decision Theory}}}, year = {{2015}}, } @article{5616, author = {{Schryen, Guido and Weishäupl, Eva}}, journal = {{Managementkompass}}, number = {{2}}, pages = {{17--18}}, publisher = {{Frankfurt Business Media, Der F.A.Z.-Fachverlag}}, title = {{{IT-Sicherheit: Ökonomisch Planen und Bewerten}}}, year = {{2015}}, } @inproceedings{5618, abstract = {{Literature reviews play an important role in the development of knowledge. Yet, we observe a lack of theoretical underpinning of and epistemological insights into how literature reviews can contribute to knowledge creation and have actually contributed in the IS discipline. To address these theoretical and empirical research gaps, we suggest a novel epistemological model of literature reviews. This model allows us to align different contributions of literature reviews with their underlying knowledge conversions - thereby building a bridge between the previously largely unconnected fields of literature reviews and epistemology. We evaluate the appropriateness of the model by conducting an empirical analysis of 173 IS literature reviews which were published in 39 pertinent IS journals between 2000 and 2014. Based on this analysis, we derive an epistemological taxonomy of IS literature reviews, which complements previously suggested typologies.}}, author = {{Schryen, Guido and Wagner, Gerit and Benlian, Alexander}}, booktitle = {{International Conference on Information Systems (ICIS)}}, keywords = {{Literature review, Research methods/methodology, Theory of knowledge}}, title = {{{Theory of Knowledge for Literature Reviews: An Epistemological Model, Taxonomy and Empirical Analysis of IS Literature}}}, year = {{2015}}, }